3 Pieces of a Puzzle
by thelastsock
Summary: Sherlock can't understand why John and Molly are even interested in each other, let alone why their relationship hasn't fizzled out already! Sometimes neither are John and Molly. It takes some deductions and confessions before Sherlock puts the pieces together, but this time Sherlock is the last one to know! Sherlock/John/Molly, Jollock


It was John's Birthday and Mrs Hudson had arranged a party for that evening at 221B. Everyone that John knew was invited, even Lestrade had managed to get the evening off. The room became full of chatter as all the guests arrived. Soon after the last guest had arrived, the lights were dimmed by Mrs Hudson. In the mild suspense that followed, Molly brought out John's birthday cake and everyone began to sing. While Sherlock simply sat in the corner, wishing he was somewhere quieter, without these tiresome celebrations.

He was bored. He'd already deduced everything about everyone in the room as a small form of entertainment. Donovan was still 'scrubbing' Andersons floors, Lestrade had recently started a relationship with a blonde woman in his block of flats, judging by the single long blonde hair on his shirt and faint lipstick stains on his lips. Everyone else was just boring. Then his eyes alighted on Molly. Her face was lit up by the flickering candles, the joke kind designed to relight after one tries to blow them out. Tedious. Molly had her eyes fixed on John, nothing unusual to note there; it was John's birthday so naturally all the attention was on him. His eyes swept to her attire, a little dressy for a small intimate party. So dressed to impress. Seeing as there were no other potential bachelors at this event, she was clearly aiming her affections at either John or himself. Molly had clearly gotten over her 'crush' on him, his assumptions based on their recent interactions in the St Bart's morgue. So that left John. A little outside her usual range of conquests but still suited to her relationship ideals.

John was smiling, if slightly embarrassed, as everyone finished singing happy birthday to him. Molly placed the cake down on the coffee table in front of John. She urged him to blow out the candles and crouched down next to the table to take pictures of the event. John smiled at the attention from her and sat forward to blow out the candles. He even joined in the laughter as the candles re-lit themselves in front of him.

Sherlock sighed; it had become obvious to him in last few weeks that John had started to form a romantic attachment to Molly too. When was he going to ask Molly on a date and get it over with so that Sherlock's life could return to normal? He was fed up of having to listen to unsubtle conversations initiated by John, before having to drag him away every time they visited the morgue.

A few hours later and everyone had left apart from Molly. She was washing up in the kitchen with John, every so often letting out a giggle. Clearly in response to some bad joke or funny medical anecdote shared between them.

Sherlock stood composing on his violin to try to solve the new case they had started a couple of days ago. After one particularly grating giggle from Molly and an accompanying chuckle from John, Sherlock had had enough. Impatient, he threw his violin onto the sofa with a growl and stormed into the kitchen.

'Will you two just go on one of those awkward 'dates' that John asks women on already so I can concentrate in silence!'

Both John and Molly jumped at Sherlock's interruption. Molly blushed furiously, before running out of the flat. John glared at Sherlock and went after her. Sherlock stalked back over the window with his violin and began playing, finally happy to have some peace.

John caught up with Molly as she reached the moonlit street outside, intent on hailing a cab. He caught her hand in his and spun her around to face him.

'Molly...'

'Shut it John. I have never been so humiliated in my life. It's fine. I know there is no way it can work, I mean you have Sherlock. And I'm always busy with -'

John cut her off mid-sentence by pressing his lips to hers. In shock, it took Molly a moment for her head to catch up and start kissing him back. A short while later they broke apart and John chuckled.

'Well I never thought I'd do that, I think I've watched too many romance movies!'

'I don't know - there's something to be said for cheesy romantic moments!' Molly replied laughing, before leaning in for another kiss.

'You sure I couldn't persuade you to stay a little longer?' John asked after another long kiss, his breath mingling with hers in the cooling night air.

'I can't, I have work early in the morning!' Molly replied, pulling a sad face. 'Besides, you owe me a date!' she finished with a smile and a wink.

Reluctantly, John hailed Molly a cab, thoroughly annoying the cab driver in the process as he kissed her at length before allowing her out of his arms. He stood on the street until the cab turned the corner and he could no longer see her face.

Sherlock turned from the window and retreated to his room. He closed the door to his room just as John entered the flat.

Sherlock spent weeks after that trying to come up with reasoning or some kind of formula or biological response as to why John and Molly seemed to form a coherent relationship together. He observed them each time they interacted whether at the morgue or at Baker Street. Mrs Hudson wasn't helping either with her constant cooing over what a sweet couple they made together. Logic said to him that John and Molly should have ceased the relationship by now; it followed the pattern of all of John's previous romantic attachments or lack thereof.

As for Molly, from his observations she had a habit of picking suitors that were either unattainable or in denial. All signs pointed to a relationship that wouldn't last.

42 days after Sherlock unwittingly brought John and Molly together he had his answer. Shortly after dawn, Sherlock was to be found in the living room of 221B. He sat in his armchair, quietly drinking a cup of tea and ruminating on his current case. Consequently, he'd sent a text to Lestrade to confirm some details and on receiving a reply to his satisfaction, continued with his deductions within his mind palace a few hours until he heard stirring from upstairs.

At around 8am, he heard John's bedroom door slam followed by Molly storming out of the flat a minute later, muttering 'Morning, Sherlock' as she left. Predictably, John came rushing out a few seconds later to witness Molly getting into a taxi.

John sat heavily on the sofa and put his head in his hands. Sherlock put his phone down on the arm of the chair and waited for John to speak.

'We had a fight. I think it's over.'

'Excellent. That means that you are free to assist me with our current case. Now there's no time to lose!' With that Sherlock threw on his coat and strode out the door. He reached the curb and flagged down a taxi, leaning in the window to give the address, before throwing himself in the back, John quietly sliding into the taxi next to him a few moments later.

As the day progressed, it became clear that John was deeply unhappy. Sherlock observed that this new reaction to John's relationships, but somehow the observations of John's love life were not as entertaining any more. When John told Sherlock his mind just wasn't on the case and he was going home for some sleep, Sherlock let him go. John wasn't even sure that Sherlock had heard him leave, but Sherlock left the scene not too long after John.

Molly sat at her desk in the mortuary; she'd hidden down here ever since she left 221B this morning. After the first text from John of 'I'm sorry. Talk at lunch?' she had turned off her phone and left it in the desk drawer. She busied herself processing all the new bodies from the night shift and prepared a couple of cadavers for a funeral home to collect later that day.

Around mid-afternoon Molly had nothing left to do. So it was almost a relief when Sherlock barrelled his way through the mortuary doors.

'Molly? I need to see the details of the post mortem on Mrs Jones of Frobisher Crescent. Where are your notes?' called Sherlock. He poked around the mortuary slabs looking at the bodies laid out. Molly hurried out of her office before Sherlock managed to cause any trouble.

'They're just over here.' indicated Molly, pulling on her lab coat and following Sherlock over to the bench.

As he perused the records, Molly's thoughts drifted to her relationship with Sherlock, confusing at the best of times and now she was breaking up with perhaps the only person who was closer to Sherlock than she was.

She wished her life could go back to before she met either of these two men who had single-handedly turned her life upside down. Sherlock looked up to see a sad but wistful look on Molly's face. There was a twinge in Sherlock's gut as Molly's eyes reached his and she pushed a smile onto her face. Sherlock sighed. He was never going to get this case finished without sorting out John and Molly. The silly notions of romance these people had.

Just as he was about to suggest to Molly that John was currently at home and that she was clearly done with work for the day, his phone rang. It was Lestrade. Unusual, as he usually text Sherlock or visited in person if he needed something.

'Sherlock, its John. Mrs Hudson says he's not turned up at Baker Street and he's not answering his phone!'

Sherlock hung up and hurriedly left the lab without a word to Molly. Not unusual for Sherlock, Molly sighed and returned to her office. She'd completely forgotten about her phone sitting silently in her desk draw.

Several hours and a lot of fast thinking later, Sherlock had managed to pinpoint John's location and retrieve him before he could come to major harm. It turned out that Sherlock had been distracted enough to overlook a small part of his current case, causing John to be kidnapped and abandoned in a soon be demolished building on the outskirts of London.

But it had been a close thing. It was past midnight before they could finally leave the scene.

The entire taxi ride back they had sat in silence, or rather Sherlock had sat deep in thought, looking out of the taxi window. As they rounded the last corner onto Baker Street, John broke the frustrating silence that had settled between them.

'Look. Sherlock. It's fine. It's not the first time I've been in danger and it won't be the last.' Sherlock turned to look at John's face. He catalogued the concrete dust in John's hair and eyelashes, the rough marks on his wrists and the mud splatters on his jeans. He noticed how exhausted John looked and a small cut just below his right ear where he'd shaved this morning. Sherlock wished he hadn't turned around.

'How could I have overlooked such an obvious flaw?' Sherlock muttered to himself, turning to look back out the window.

They pulled up outside 221B and stepped out of the cab but before either of them could reach the front door, Molly came running out, her face pale.

'Oh my God! John, are you ok? Lestrade rang the mortuary and told me you were missing but I hadn't heard anything for hours and I just...' she paused and then launched herself at John, kissing every part of his face she could reach. Mrs Hudson looked on from the doorway smiling.

'Molly,' John chuckled weakly. 'Molly! I'm fine! All I really need right now is a shower!' He took her hand and led her into the flat.

Sherlock followed at a slower pace, apologising to Mrs Hudson for worrying her as he passed her in the corridor on the way upstairs. Upon entering the living room, Molly called out to him.

'Sherlock? That you? Would you like a cup of tea?'

He replied with an affirmative, hung up his coat and a few moments later, Molly came into the room carrying three mugs of tea. One clearly John's army service mug, one a slightly feminine mug Molly favoured whenever she was over. The third mug, to Sherlock's surprise, was the mug he preferred to drink tea out of after cases. A mug large enough for his hands to wrap around and the larger volume of tea to restore energy deficit incurred whilst on a case. She set them down and handed over Sherlock's mug before tucking herself neatly onto the sofa next to him. He felt like he'd underestimated the mousey women sitting next to him as he took a sip of his tea, made just how he always liked it.

'Molly, I...' Sherlock started hesitantly, looking down at his mug.

'Shh, Sherlock, it's fine, he's back in one piece.' Molly replied in a soothing voice.

'I want, no need, to apologise...I should've realised you'd...' Sherlock babbled quickly. He stopped, visibly collected himself and sighed exasperatedly. 'It won't happen again. I'll keep John safe. I promise.'

'I know... Well I know you'll at least try!' Molly replied half-jokingly. 'Thanks for bringing him back to me.'

They sat in a slightly awkward silence, punctuated only by Molly's yawning and the occasional sips of tea from the pair. To Sherlock's relief, they heard John's footsteps heading towards them shortly after.

'Ah that's better!' John said, padding barefoot into the living room in a clean pair of trousers and an old jumper. Sherlock noted that John never wore this jumper outside, good thing too as it had several small holes in it. But he always seemed to wear it after particularly distressing cases, a comforting object no doubt.

As John approached the sofa, Sherlock jumped up to make room for him next to Molly. John settled onto the sofa and snuggled next to Molly. Sherlock still didn't understand how they could be so comfortable with each other, even though they'd had a seemingly catastrophic seeming disagreement only this morning. Whenever he'd witnessed John's previous relationships ending, there was always a sense of awkwardness as his 'dates' left the flat. He went to sit over in his armchair on the other side of the room to leave them together. Or he would have tried to, had a small hand not reached out to grab onto his jacket.

Sherlock looked down in bemusement at the hand and saw that it belonged to Molly. Following her arm with his gaze, he reached her face, still slightly red and puffy from tears but with a fierce look of determination in her eyes that Sherlock had scarcely seen there before. After a few seconds deliberation he decided it was not worth arguing with Molly today so settled back onto the far end of the sofa with good grace to watch whatever drivel it was the Molly had been attempting to watch earlier.

The sun had just begun to rise, before either John or Sherlock realised that Molly had fallen asleep. John gently nudged Sherlock's shoulder from where his free hand was resting along the back of the sofa, the other being occupied by Molly's hand. Sherlock looked away from the mildly diverting sci-fi series on in the background that had replaced the romantic comedy Molly had insisted on watching. Sherlock loved to deduce the endings to any programmes, much to the annoyance of anyone watching with him.

John gestured towards Molly and her sleeping form. She was resting in what Sherlock thought a highly awkward position, with her head and shoulders in John's lap facing towards the TV and her legs draped over the arm of the sofa.

The slight movements caused by their silent conversation caused Molly to shuffle in her sleep and to the men's surprise, reached out for Sherlock's hand across the small sofa. She tugged both their hands so that their hands rested gently on her chest. Sherlock shifted uncomfortably on sofa, feeling awkward in this highly domestic situation but found it difficult to find reasons to get up. He turned back to the programme, trying to ignore the warmth from Molly's hand and the smirk on John's face.

A short while later the credits rolled on the programme, Sherlock have only moments before explained the entire premise for the season's storyline in the show. John looked over at him, a slight annoyance gracing his features briefly before he began to chuckle quietly.

'Sherlock! You realise you've had a smile on your face the entire time we've been watching this programme? You don't normally find this kind of programme so entertaining!' John teased.

Sherlock turned towards John, finding him a little bit closer than expected and cleared his throat hastily.

'I think you'll find 'entire time we've been watching' to be a bit of an exaggeration John.' He replied haughtily and turned back towards the TV, the edges of his ears a slight pink.

This just made John laugh harder. He laughed hard enough to shake Molly awake. She let go of Sherlock's hand as she stretched, accidentally grazing Sherlock's thigh as she did so. Unbeknownst to Molly, the flush that had been slowly dissipating in the brief moments after John had succeeded in embarrassing Sherlock, came back with full force, spreading to the back of his neck.

'Well hello there Molly love, you back with us at last?' John said softly, as Molly opened her eyes.

On hearing this term of endearment, Molly grinned and pulled herself upright into John's lap.

'Oh, I fell asleep? I must have been shattered! How long was I out for?'

John glanced at his watch, but before he could reply, Sherlock interrupted him, his eyes not leaving the TV, even as he spoke.

'About 2 hours, give or take roughly 10 minutes either way as neither John nor I made a measure of when you entered your sleep cycle. Your pulse or rate of breathing would have been an adequate measure which could have been easily obtained, had I known you would request such information after the fact.'

Molly smiled at Sherlock's response to her question and stretched again, apologising a few seconds later as she nudged John in the face with her elbow.

Soon, both she and John were laughing at one end of the sofa. Sherlock sat still at the other end of the sofa bemused as to the strange reaction from the couple who had previously been angry each other for most of the day. Sherlock left the living room, collecting everyone's mugs as he went, intending on making everyone another cup of tea.

As Sherlock left the room, Molly moved off of John's lap onto the sofa next to him and turned to face him. They both started speaking at the same time.

'I'm sorry...'

They stopped and smiled at each other, their earlier argument mainly forgotten. There was just one thing that Molly needed to discuss before it was settled. Now the look of determination that Molly was so very good at, was directed at John. He made a mental note that he should try and avoid incurring this kind of look off of Molly ever again.

'John, you hurt me so much when you suggested that I wasn't putting my all into this relationship. That I was waiting for_ 'someone'_ better to come along. You think I'm not aware of what people have said about me? I thought you were the one person who would understand.' Molly paused, on the brink of tears, a few moments later she sniffed,

'I can't stay mad because I feel so guilty knowing that I could have prevented all this, if I hadn't been so stubborn and ignored your message this morning!'

'Hush, its ok Molly, I'm still here aren't I?' John said as he wiped away her tears. Clearing his throat, he continued,

'You can stay mad at me for as long as you like, I deserve it! I'm stupid and a complete bastard for even thinking of accusing you of those things! I know it doesn't excuse what I said but I was jealous and scared. Now, I've had a lot of time to myself to think today.' Molly winced, glancing at the still raw marks on John's wrists. He took a deep breath, steeling himself. 'And... You were right. That jealousy of mine works both ways, same as your affection.' John finished pointedly, a shy smile on his face.

Molly stared at him. At that moment, she reckoned she fell in love with him all over again. Sweet, dependable John was admitting to her that they clearly felt the same way.

About _Sherlock_.

Tension broken, they both laughed loudly, before attempting to stifle further giggles, afraid they would wake the neighbours.

Meanwhile, Sherlock leant against the countertop in the dim kitchen, his mind focused elsewhere than on the current happenings in the other room. Now that the case he had been working on earlier had been solved - merely a case of a couple of minutes of deduction after they had located John - he was left to analyse the remainder of the day.

His mind whirred as the kettle boiled, he felt like he was missing something obvious, like a jigsaw piece that had fallen under the table, to be covered up over time and only to be revealed when it was no longer important. It drove Sherlock mad. Frustrated, he began reciting the periodic table in his head to re-gather his thoughts.

Then he remembered the touch of Molly's hand in his, the warmth and comfort of this and close proximity of his friends as they had sat together. He felt a smile appear on his face, how had these people managed to get so close?

He was jogged out of these thoughts by the kettle clicking off. He heard murmuring from the living room, followed by laughter. Clearly John and Molly had sorted out their differences. Sherlock was fairly sure he knew what they had been arguing about but wanted to deduce out loud in front of them both.

John hadn't been nearly impressed enough Sherlock's deductions of the ridiculous and childish sci-fi programme they'd been watching earlier. Molly wasn't even awake to hear Sherlock's reasoning for re-writing previous seasons because they had major plot holes in that were easily solved if only they had asked even the simplest of people to check their writing.

So he walked back out of the kitchen, forgetting about the kettle slowly cooling behind him, for there were deductions to be made.

Molly was once again sitting in John's lap when Sherlock entered the room; they abruptly stopped giggling as Sherlock stopped in front of them.

'So you've resolved your disagreement earlier this morning that Molly wasn't putting enough effort into your relationship John?'

Molly blushed and a look of discomfort crossed John's face.

'Well it was obvious that you had said something to Molly this morning to cause her to leave in a rush this morning, quite unlike her usual talkative self. Not to mention the text message I saw you send to her while we were at the crime scene earlier today.'

Sherlock was enjoying himself. They had looks of shock rather than amazement on their faces but it would have to do.

'Furthermore, when I entered Bart's, Molly did not look up from her desk when I entered the lab, which has been customary since the two of you entered into a relationship. This evening, I surmised that you, Molly, would have already forgiven John for the earlier indiscretion, given the guilty feeling from ignoring John's text messages all day, but there was still some tension lingering between you two, just below the surface. Not enough to create outward awkwardness but something that needed discussion. So when I left the room, you took the opportunity to resolve the issue out of my hearing.'

Sherlock had been pacing while he expounded on his theory, now he stood still, ready for the final flourish and ultimate reactions of John and Molly. For the moment, they merely sat with similar, although muted expressions, as when Sherlock began his deductions about the couple.

'Now it must have been an issue that was subconsciously already solved by one or both parties, as I was gone for no longer than 5 minutes. Given these points of data and John's tendency to be protective, I can only assume that he was jealous of an interaction between you and someone you both interacted with at Bart's.'

Sherlock stopped here, neglecting to mention the additional observations that he had noted about these companions of his earlier in the day. Sherlock, sensing victory, sat on the couch as he waited for the couple to reply. This time Molly took the lead. She started laughing. Sherlock looked bemused; this was not the reaction he was expecting. After Molly had calmed down, she began to explain.

'Once again Sherlock, your deductions are spot on. But there's one part you may have overlooked in your haste to reach the conclusion. Since John and I got to together he's been helping out in the lab from time to time, as they haven't hired an assistant to help me during shifts in the mortuary yet. So I don't have co-workers for John to get jealous of.' She paused. 'Well I suppose technically I do...' Molly finished with a wry smile, seeing that Sherlock was still looking confused. Molly turned to look at John; he nodded and picked up where she left off.

'For the world's only consulting detective, you can be dense sometimes! Me and Molly, we work right? But for her, there was, is always you. She could try to deny it all she liked but I knew. Thing is though, I wasn't jealous of you. I was jealous of _Molly_. I'm ashamed to say it took me a while to figure it out, but she's right you know. There's just something about you Sherlock.'

John smiled at Sherlock, a faint pink flush present on his face. Molly was smiling too, but a little more nervously.

'What we're saying Sherlock, is that our relationship isn't complete without you.'

A thick silence fell over the room and John and Molly waited in anticipation.

In the first moments after this confession, Sherlock's thoughts were caught up on the fact that Molly had said that he'd missed a key part. For the second time that day, he felt an almost crushing guilt. Now he felt like he was letting his closest friends down by not even being able to deduce an argument between them.

He wondered if he had become weak by allowing these people into his life, he was perfectly fine before they ever entered his life. So why were they so important now?

He began cataloguing all observations of the couple in front of him. He started with Molly's messily tied hair, made worse by her decision to sleep on the couch earlier, down to her chest, where he noticed she was in fact wearing one of John's other jumpers. Following her arm down to where her hand was clasped in John's.

Now John. That baggy old jumper, John's favourite, reluctant to throw it out it became a kind of lounging around jumper. Always smells like John. Down to his bare feet, which were now tapping nervously on the carpet.

Wait. What did Molly just say? And John?

Nervous smiles. Flushed faces. Signals attraction or confessions.

Sherlock's mind being flooded with these observations and deductions had only just caught up with what Molly and John told him. Finally, he found the missing piece of puzzle he'd been agonising over. Well, _pieces_ if he wanted to be precise.

'Well then we'll need to get boxes, hire a removal van and I'll have to do some research.' Sherlock replied after what felt like an age to John and Molly.

'What?' John replied, confused as to Sherlock's sudden outburst.

'Well Molly will have to move into Baker Street, we'll have to buy a new bed big enough for the three of us and I'll have to research how this whole relationship idea works, as I have not gained suitable conclusions from observing you two. Not surprising now your preferences have come to light.'

After a stunned silence from Molly she began laughing, John joining in a few seconds later.

'I'm glad we have haven't scared you off Sherlock! But take it easy, we've got all the time we need to sort things like that out!' Molly replied with a grin on her face.

'We know you aren't too familiar with how relationships work Sherlock, but it's ok, we don't need you doing crazy amounts of detailed research. We can go at whatever pace or level you're comfortable with.' John added, hesitantly placing his hand on top of Sherlock's. He breathed a sigh of relief as Sherlock turned his hand to squeeze John's hand.

The sun had fully risen by this point but John and Molly were exhausted from the night's events, so saying goodnight to Sherlock, they retired to bed. Sherlock insisted he wasn't tired but a short while later, Sherlock found his eyelids drooping.

He walked to his bedroom and changed into his pyjamas, looking over at his empty bed. Now he knew John and Molly's intentions he was reluctant to spend the night in his bed alone and cold. So he snuck up to their bedroom and quietly opened the door. He paused on the threshold, still unsure as to whether he should join them or not.

'Sherlock, just get in here.' John said sleepily. Molly murmured in assent and shuffled over so that there was room for Sherlock to join them. His heart a little lighter, Sherlock gladly tucked himself in among his friends and was almost instantly asleep.

**A/N: Well that was my first Sherlock fic, I hope that it wasn't too awful and that you enjoyed it! It originated as a challenge on Tumblr a while back but inspiration was lacking until the summer, so here we are now :) Constructive criticism is welcome! **


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